Cardiac magnetic resonance for early atrial lesion visualization post atrial fibrillation radiofrequency catheter ablation

BACKGROUND

Incomplete atrial lesions resulting in pulmonary vein-left atrium reconnection after pulmonary vein antrum isolation (PVAI), are related to atrial fibrillation (AF) recurrence. Unfortunately, during the PVAI procedure, fluoroscopy and electroanatomic mapping cannot accurately determine the location and size of the ablation lesions in the atrial wall and this can result in incomplete PVAI lesions (PVAI-L) after radiofrequency catheter ablation (RFCA).

AIM

We seek to evaluate whether cardiac magnetic resonance (CMR), immediately after RFCA of AF, can identify PVAI-L by characterizing the left atrial tissue.

METHODS

Ten patients (63.1 ± 5.7 years old, 80% male) receiving a RFCA for paroxysmal AF underwent a CMR before (<1 week) and after (<1 h) the PVAI. Two-dimensional dark-blood T2-weighted short tau inversion recovery (DB-STIR), Three-dimensional inversion-recovery prepared long inversion time (3D-TWILITE) and three-dimensional late gadolinium enhancement (3D-LGE) images were performed to visualize PVAI-L.

RESULTS

The PVAI-L was visible in 10 patients (100%) using 3D-TWILITE and 3D-LGE. Conversely, On DB-STIR, the ablation core of the PAVI-L could not be identified because of a diffuse high signal of the atrial wall post-PVAI. Microvascular obstruction was identified in 7 (70%) patients using 3D-LGE.

CONCLUSION

CMR can visualize PVAI-L immediately after the RFCA of AF even without the use of contrast agents. Future studies are needed to understand if the use of CMR for PVAI-L detection after RFCA can improve the results of ablation procedures.

Cardiac magnetic resonance-guided cardiac ablation: a case series of an early experience

Radiofrequency (RF) catheter ablation has become a widely used therapeutic approach. However, long-term results in terms of arrhythmia recurrence are still suboptimal. Cardiac magnetic resonance (CMR) could offer a valuable tool to overcome this limitation, with the possibility of targeting the arrhythmic substrate and evaluating the location, depth, and possible gaps of RF lesions. Moreover, real-time CMR-guided procedures offer a radiation-free approach with an evaluation of anatomical structures, substrates, RF lesions, and possible complications during a single procedure. The first steps in the field have been made with cavotricuspid isthmus ablation, showing similar procedural duration and success rate to standard fluoroscopy-guided procedures, while allowing visualization of anatomic structures and RF lesions. These promising results open the path for further studies in the context of more complex arrhythmias, like atrial fibrillation and ventricular tachycardias. Of note, setting up an interventional CMR (iCMR) centre requires safety and technical standards, mostly related to the need for CMR-compatible equipment and medical staff's educational training. For the cardiac imagers, it is fundamental to provide correct CMR sequences for catheter tracking and guide RF delivery. At the same time, the electrophysiologist needs a rapid interpretation of CMR images during the procedures. The aim of this paper is first to review the logistic and technical aspects of setting up an iCMR suite. Then, we will describe the experience in iCMR-guided flutter ablations of two European centres, Policlinico Casilino in Rome, Italy, and Haga Teaching Hospital in The Hague, the Netherlands.